<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
			.transitionBox{
				width: 100px;
				height: 100px;
				background-color: red;
				
				/*横向拉伸*/
				transition: width 2s;
				
				
				
			}
			/*动画触发：鼠标移入触发*/
			.transitionBox:hover{
				width: 300px;
				
			}
		</style>
	</head>
	<body>
		<h3>拉伸一个盒子</h3>
		<h5>transition有两个参数：拉伸方向width,2s动画执行时间</h5>
		<div class="transitionBox"></div>
	</body>
</html>
